DO NOT ruin the fantasy of Supergirl by putting Lana in the costume!
As much as I hate her character's whiney attitude over the years she definately somehow seems hotter when she's being bad.
I do wonder if she'll go over the line and then we'll learn that this has been Lana's clone the whole time.
That would actually suck, though because 'boring whiny Lana' would be back.
I'd rather see one of the the bad versions of Lana stick around even if it was the evil witch, Countess Isobel again.
It's wierd because as much as I like Smallville, I've always found the characters more interesting when they turn evil. Even Clark is more interesting when he's infected with red-kryptonite.